基于自感应复合纤网的真空树脂传递模塑成型固化过程原位监测

In-situ monitoring of VARTM curing process based on self-sensing C-GNS

为了实现对复合材料加工固化全过程的原位、实时在线监测,以高孔隙率玻璃纤维非织造布为传感骨架、多壁碳纳米管(MWCNT)为导电纳米颗粒,采用超声雾化喷涂工艺,构建了一种高扩展的压阻型CNT非织造复合纤网(C-GNS)。在复合材料真空辅助树脂传递模塑(VARTM)成型固化过程中,实时采集C-GNS的电阻响应并建立其与树脂基体固化行为之间的量化关系。结果表明:该复合纤网具有缠结、松散的多孔网络结构,能与树脂充分浸渍,并实现对树脂固化过程的关键相转变点(固化起始点、凝胶点、完全固化)精准高效地原位监测,C-GNS的过程电阻增益因子达80%。研究结果为复合材料VARTM成型加工制造提供了一种有效的固化监测手段,进一步拓展了自感应非织造复合材料的多功能应用。

Advanced composite materials are widely used in navigation,shipbuilding,automobile and civil industries because of their high specific modulus,strength,corrosion resistance and impact resistance.However,due to the limitations of manufacturing and detection technology,the superior performance of composite materials can not be fully displayed.Common liquid composite molding processes such as resin transfer molding(RTM)and vacuum assisted resin transfer molding(VARTM)encounter difficulties in the application of processing large-scale composite materials.For example,due to the lack of real-time monitoring methods,it is impossible to accurately know whether the resin in the curing process is fully cured and whether there is residual stress,which ultimately results in difficulty in ensuring product quality.In order to guarantee the quality of composite material products and the repeatability of production,it is necessary to conduct in-situ real-time monitoring of the curing process of composite materials.In this study,the ultra-thin,dense and uniform MWCNT conductive induction coating was constructed on the surface of high-porosity glass fiber nonwovens by ultrasonic atomized spraying technology,and the in-situ and real-time monitoring ability of the resin curing process in VARTM molding process was systematically analyzed.The results indicated that the C-GNS showed good response sensitivity(up to 16.77 Pa~(-1))in the detection process of vacuum calendering process at room temperature.In addition,the C-GNS resistor responded instantly,and could directly map the whole curing process of thermoset epoxy resin under the combined action of temperature field and pressure field and the key points(starting point of curing,starting point of gelation,gel point and complete curing)of phase transition involved in the process.Specifically,during the whole curing process,the resistance gain factor of the sensor reached up to 80%,and the real-time resistivity changes were highly consistent with the resin curing kinetic behavior measured by differential scanning calorimetry,rheology and dielectric curing.This study provides an effective curing monitoring method(C-GNS)for VARTM processing and manufac-turing,and further expands the multi-functional applications of self-sensing nanocarbon composites.